1. Field of the Invention
The present invention relates to a bump stopper used in a vehicular suspension, a shock absorber or the like.
2. Description of the Conventional Art
In a vehicular suspension apparatus supporting a knuckle rotatably supporting a wheel to a vehicle body via a suspension arm so as to be movable up and down, a bump stopper is used in a vehicle body side. In other words, the bump stopper is installed to the vehicle body side, and opposes to a collision surface provided in an upper surface of the suspension arm in a contactable manner. When the vehicle body bumps largely while compressing a suspension spring, that is, when the vehicle body moves down in a direction of coming close to a road surface, the bump stopper comes into contact with the collision surface of the arm, thereby regulating a maximum bump amount of the vehicle body.
A bump stopper 51 having the function mentioned above is formed in a cylindrical shape by a rubber-like elastic body as shown in FIG. 5A, is provided with a constricted part 52 in a circumferential surface so as to be formed as a bellows shape, and is elastically deformed at a time of coming into collision with a collision surface 62 of an arm 61 by an annular distal end portion 53 in an axial direction so as to achieve a buffering action. The bump stopper distal end portion 53 has an outside diameter becoming smaller toward a distal side and is formed in a thin shape for buffering a primary shock.
Further, there are the bump stoppers for a front side and a rear side. Among them, since the front bump stopper is supported by a rod of an absorber, it comes into collision in such a state that a central axis of the bump stopper is orthogonal to the collision surface. However, since the rear bump stopper 51 is not supported by another part, it comes into collision in such a state that a bump stopper central axis O is inclined with respect to the collision surface 62 of the arm 61 as illustrated.
Accordingly, in the latter rear bump stopper, since a collision start point 54 of the bump stopper distal end portion 53 is positioned at the inclined side with respect to a bump stopper thickness, the bump stopper distal end portion 53 starts slipping on the collision surface 62 of the arm 61 from the collision time as shown in FIG. 5B (an arrow A), the slip is promoted together with the compression of the bump stopper 51, and there is a disadvantage that a noise (an abnormal noise) is generated at this time.
Reference is made to Japanese Unexamined Patent Publication No. 2006-69463, Japanese Unexamined Patent Publication No. 9-79305, and Japanese Unexamined Patent Publication No. 9-52505.